scholarly journals The role of the type VI secretion system vgrG gene in the virulence and antimicrobial resistance of Acinetobacter baumannii ATCC 19606

PLoS ONE ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. e0192288 ◽  
Author(s):  
Jianfeng Wang ◽  
Zhihui Zhou ◽  
Fang He ◽  
Zhi Ruan ◽  
Yan Jiang ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Acinetobacter Baumannii ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Type Vi Secretion

scholarly journals Identification of Novel Acinetobacter baumannii Type VI Secretion System Antibacterial Effector and Immunity Pairs

2018 ◽  
Vol 86 (8) ◽  
Author(s):  
Timothy C. Fitzsimons ◽  
Jessica M. Lewis ◽  
Amy Wright ◽  
Oded Kleifeld ◽  
Ralf B. Schittenhelm ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Type Vi Secretion System ◽  
Acinetobacter Baylyi ◽  
Content Type ◽  
Type Vi Secretion ◽  
Immunity Genes

ABSTRACT The type VI secretion system (T6SS) is a macromolecular machine that delivers protein effectors into host cells and/or competing bacteria. The effectors may be delivered as noncovalently bound cargo of T6SS needle proteins (VgrG/Hcp/PAAR) or as C-terminal extensions of these proteins. Many Acinetobacter baumannii strains produce a T6SS, but little is known about the specific effectors or how they are delivered. In this study, we show that A. baumannii AB307-0294 encodes three vgrG loci, each containing a vgrG gene, a T6SS toxic effector gene, and an antitoxin/immunity gene. Each of the T6SS toxic effectors could kill Escherichia coli when produced in trans unless the cognate immunity protein was coproduced. To determine the role of each VgrG in effector delivery, we performed interbacterial competitive killing assays using A. baumannii AB307-0294 vgrG mutants, together with Acinetobacter baylyi prey cells expressing pairs of immunity genes that protected against two toxic effectors but not a third. Using this approach, we showed that AB307-0294 produces only three T6SS toxic effectors capable of killing A. baylyi and that each VgrG protein is specific for the carriage of one effector. Finally, we analyzed a number of A. baumannii genomes and identified significant diversity in the range of encoded T6SS VgrG and effector proteins, with correlations between effector types and A. baumannii global clone lineages.

scholarly journals Multidrug-resistant plasmids repress chromosomally encoded T6SS to enable their dissemination

2019 ◽  
Vol 116 (4) ◽  
pp. 1378-1383 ◽  
Author(s):  
Gisela Di Venanzio ◽  
Ki Hwan Moon ◽  
Brent S. Weber ◽  
Juvenal Lopez ◽  
Pek Man Ly ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Acinetobacter Baumannii ◽  
Multidrug Resistant ◽  
Secretion System ◽  
Cell Contact ◽  
Nosocomial Pathogen ◽  
Type Vi Secretion System ◽  
Active Type ◽  
Type Vi Secretion ◽  
Plasmid Conjugation

Acinetobacter baumannii (Ab) is a nosocomial pathogen with one of the highest rates of multidrug resistance (MDR). This is partially due to transmissible plasmids. Many Ab strains harbor a constitutively active type VI secretion system (T6SS) that is employed to kill nonkin bacteria. T6SS and plasmid conjugation both involve cell-to-cell contact. Paradoxically, successful conjugation requires the survival of the recipient, which is the target of the T6SS. Thus, an active T6SS in either the donor or the recipient poses a challenge to plasmid conjugation. Here, we show that large conjugative MDR plasmids heavily rely on their distinctive ability to repress the T6SS of their hosts to enable their own dissemination and the conjugation of other plasmids, contributing to the propagation of MDR among Acinetobacter isolates.

scholarly journals Acinetobacter baumannii Utilizes a Type VI Secretion System for Bacterial Competition

PLoS ONE ◽  
2013 ◽  
Vol 8 (3) ◽  
pp. e59388 ◽  
Author(s):  
Michael D. Carruthers ◽  
Paul A. Nicholson ◽  
Erin N. Tracy ◽  
Robert S. Munson
Keyword(s):  
Acinetobacter Baumannii ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Bacterial Competition ◽  
Type Vi Secretion

scholarly journals Beyond dueling: roles of the type VI secretion system in microbiome modulation, pathogenesis and stress resistance

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Jinshui Lin ◽  
Lei Xu ◽  
Jianshe Yang ◽  
Zhuo Wang ◽  
Xihui Shen
Keyword(s):  
Stress Resistance ◽  
Secretion System ◽  
Bacterial Cells ◽  
Type Vi Secretion System ◽  
Secretion Systems ◽  
Competitive Fitness ◽  
Type Vi Secretion ◽  
Protein Secretion Systems ◽  
Extracellular Environment

AbstractBacteria inhabit diverse and dynamic environments, where nutrients may be limited and toxic chemicals can be prevalent. To adapt to these stressful conditions, bacteria have evolved specialized protein secretion systems, such as the type VI secretion system (T6SS) to facilitate their survival. As a molecular syringe, the T6SS expels various effectors into neighboring bacterial cells, eukaryotic cells, or the extracellular environment. These effectors improve the competitive fitness and environmental adaption of bacterial cells. Although primarily recognized as antibacterial weapons, recent studies have demonstrated that T6SSs have functions beyond interspecies competition. Here, we summarize recent research on the role of T6SSs in microbiome modulation, pathogenesis, and stress resistance.

scholarly journals VgrG-dependent effectors and chaperones modulate the assembly of the type VI secretion system

2021 ◽  
Vol 17 (12) ◽  
pp. e1010116
Author(s):  
Xiaoye Liang ◽  
Tong-Tong Pei ◽  
Hao Li ◽  
Hao-Yu Zheng ◽  
Han Luo ◽  
...  
Keyword(s):  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Structural Proteins ◽  
Wild Type ◽  
Type Vi Secretion System ◽  
Double Deletion ◽  
Type Vi Secretion ◽  
Structural Determinant

The type VI secretion system (T6SS) is a spear-like nanomachine found in gram-negative pathogens for delivery of toxic effectors to neighboring bacterial and host cells. Its assembly requires a tip spike complex consisting of a VgrG-trimer, a PAAR protein, and the interacting effectors. However, how the spike controls T6SS assembly remains elusive. Here we investigated the role of three VgrG-effector pairs in Aeromonas dhakensis strain SSU, a clinical isolate with a constitutively active T6SS. By swapping VgrG tail sequences, we demonstrate that the C-terminal ~30 amino-acid tail dictates effector specificity. Double deletion of vgrG1&2 genes (VgrG3+) abolished T6SS secretion, which can be rescued by ectopically expressing chimeric VgrG3 with a VgrG1/2-tail but not the wild type VgrG3. In addition, deletion of effector-specific chaperones also severely impaired T6SS secretion, despite the presence of intact VgrG and effector proteins, in both SSU and Vibrio cholerae V52. We further show that SSU could deliver a V. cholerae effector VasX when expressing a plasmid-borne chimeric VgrG with VasX-specific VgrG tail and chaperone sequences. Pull-down analyses show that two SSU effectors, TseP and TseC, could interact with their cognate VgrGs, the baseplate protein TssK, and the key assembly chaperone TssA. Effectors TseL and VasX could interact with TssF, TssK and TssA in V. cholerae. Collectively, we demonstrate that chimeric VgrG-effector pairs could bypass the requirement of heterologous VgrG complex and propose that effector-stuffing inside the baseplate complex, facilitated by chaperones and the interaction with structural proteins, serves as a crucial structural determinant for T6SS assembly.

scholarly journals Light Modulates Metabolic Pathways and Other Novel Physiological Traits in the Human Pathogen Acinetobacter baumannii

2017 ◽  
Vol 199 (10) ◽  
Author(s):  
Gabriela L. Müller ◽  
Marisel Tuttobene ◽  
Matías Altilio ◽  
Maitena Martínez Amezaga ◽  
Meaghan Nguyen ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Metabolic Pathways ◽  
Secretion System ◽  
Human Pathogen ◽  
Type Vi Secretion System ◽  
Bacterial Persistence ◽  
Content Type ◽  
Light Sensing ◽  
Type Vi Secretion ◽  
Novel Concept

ABSTRACT Light sensing in chemotrophic bacteria has been relatively recently ascertained. In the human pathogen Acinetobacter baumannii, light modulates motility, biofilm formation, and virulence through the blue-light-sensing-using flavin (BLUF) photoreceptor BlsA. In addition, light can induce a reduction in susceptibility to certain antibiotics, such as minocycline and tigecycline, in a photoreceptor-independent manner. In this work, we identified new traits whose expression levels are modulated by light in this pathogen, which comprise not only important determinants related to pathogenicity and antibiotic resistance but also metabolic pathways, which represents a novel concept for chemotrophic bacteria. Indeed, the phenylacetic acid catabolic pathway and trehalose biosynthesis were modulated by light, responses that completely depend on BlsA. We further show that tolerance to some antibiotics and modulation of antioxidant enzyme levels are also influenced by light, likely contributing to bacterial persistence in adverse environments. Also, we present evidence indicating that surfactant production is modulated by light. Finally, the expression of whole pathways and gene clusters, such as genes involved in lipid metabolism and genes encoding components of the type VI secretion system, as well as efflux pumps related to antibiotic resistance, was differentially induced by light. Overall, our results indicate that light modulates global features of the A. baumannii lifestyle. IMPORTANCE The discovery that nonphototrophic bacteria respond to light constituted a novel concept in microbiology. In this context, we demonstrated that light could modulate aspects related to bacterial virulence, persistence, and resistance to antibiotics in the human pathogen Acinetobacter baumannii. In this work, we present the novel finding that light directly regulates metabolism in this chemotrophic bacterium. Insights into the mechanism show the involvement of the photoreceptor BlsA. In addition, tolerance to antibiotics and catalase levels are also influenced by light, likely contributing to bacterial persistence in adverse environments, as is the expression of the type VI secretion system and efflux pumps. Overall, a profound influence of light on the lifestyle of A. baumannii is suggested to occur.

Sign in / Sign up

Export Citation Format

Share Document